1. Field of the Invention
The present invention relates to a mounting fixture which is used for mounting a ring-shaped elastic seal member on a peripheral surface of an optical component such as a partial reflecting mirror or full reflecting mirror.
2. Description of the Related Art
A laser oscillator used for cutting, welding, and otherwise processing metal is provided with various optical components such as partial reflecting mirrors and full reflecting mirrors. Usually, these optical components are built into the laser oscillator while mounted on dedicated holders. Further, in order to secure the vacuum state or air-tight state around the optical components and to prevent the optical components from being subjected to mechanical stress, the optical components are mounted on holders through elastic seal members such as O-rings or gaskets. In particular, in gas laser oscillators, O-rings for securing the air-tightness of the flow paths of the gas are mounted on the side surfaces of the optical components such as partial reflecting mirrors and full reflecting mirrors. The seal structure of such an optical component is illustrated in JP S63-229780A. Similarly, in a processing head of a laser processing machine, an O-ring or gasket for cutting off the assist gas is mounted on the side surface of the optical component.
Incidentally, when an optical component of a laser oscillator or laser processing machine is detached for cleaning or replacement, it is necessary to proceed with mounting the cleaned optical component or new optical component again on the holder. Such mounting of the optical component includes mounting the elastic seal members such as O-rings or gaskets on the side surface of the optical component again. FIG. 14 to FIG. 18 are schematic views which show by time series the procedure in the mounting work of an optical component in a conventional CO2 gas laser.
In FIG. 14, the holder (mirror holder 7) for holding an optical component (mirror 6) is detached from a resonator. In the state of FIG. 14, a large diameter O-ring 8 is located between a side surface 61 of the mirror 6 and a circumferential wall part 72 of the mirror holder 7, while a small diameter O-ring 9 is located between the bottom surface 63 of the mirror 6 and a support part 71 of the mirror holder 7. These O-rings 8 and 9 not only perform the function of maintaining the vacuum state of the resonator, but also the function of positioning the mirror 6 at the center of the mirror holder 7. Next, in FIG. 15, the mirror 6 is detached from the mirror holder 7 to be placed on a flat mirror table T. After the mirror 6 is brought into the state of FIG. 15, the cleaning operation of the bottom surface 63 of the mirror 6 is started. At the end of the cleaning operation, cleaning paper CP is used to wipe the bottom surface 63 to finish it up. Next, in FIG. 16, the mirror 6 is again placed on the mirror holder 7. In the state of FIG. 16, the small diameter O-ring 9 is mounted in advance between the bottom surface 62 of the mirror and the support part 71 of the mirror holder 7.
Next, FIG. 17 shows the intermediate state where a large diameter O-ring 8 is mounted between the mirror 6 and the mirror holder 7. As shown in FIG. 17, in the mounting work according to this example, the worker uses his fingers to press the O-ring 8 downward so as to mount the O-ring 8 between the side surface 61 of the mirror 6 and the circumferential wall part 72 of the mirror holder 7. During this step, the worker preferably uses the fingers of his two hands to uniformly press a plurality of locations of the O-ring 8 in the circumferential direction. This ensures that the O-ring 8 is pressed into the ring-shaped groove between the side surface 61 of the mirror 6 and the mirror holder 7. Note that, the circumferential wall part 72 of the mirror holder 7 is designed so that the O-ring 8 can be mounted in a suitably compressed form.
However, in mounting with the fingers of a worker, non-uniform pressing force may be applied to various parts of the O-ring 8 in the circumferential direction due low skill of the worker, and therefore the O-ring 8 is liable to be mounted in a slanted posture with respect to the mirror 6 or mirror holder 7. Alternatively, the O-ring 8 may stick out from the above ring-shaped groove because of manufacturing error of the mirror holder 7 and O-ring 8 or swelling of the O-ring 8 due to aging, and therefore the O-ring 8 is liable to be mounted slanted with respect to the mirror holder 7. If the O-ring 8 is mounted in a slanted posture in this way, the mirror 6 is liable to rise up from the mirror holder 7 due to the elastic recovery force of the O-ring 8.
FIG. 18 shows an O-ring 8 which is mounted in a posture slanted with respect to the mirror holder 7. In the state of FIG. 18, part of the O-ring 8 sticks out from the ring-shaped groove. As a result, the bottom surface 63 of the mirror 6 rises up from the mirror holder 7. Further, if the fingers of the worker mistakenly touch the mirror 6 during the mounting of the O-ring 8, the coating of the mirror 6 may be scratched or some contaminant may be deposited on the mirror 6. Further, if the worker repeatedly tries to mount the O-ring 8 with respect to the mirror 6 and mirror holder 7 in a horizontal posture, the mounting work of the O-ring 8 will take a longer time. Furthermore, if the pushing depth of the O-ring 8 into the above ring-shaped groove is insufficient, the O-ring 8 will stick out upward from the top surface 62 of the mirror 6, and thus obstruct cleaning of the top surface 62 to be performed afterward.
A mounting fixture which enables a worker to accurately mount an elastic seal member between an optical component and holder without directly touching the optical component has been sought.